Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 201737 AAC
AFDFFC

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1237 PM EST SAT DEC 20 2014

.PREV DISCUSSION... /ISSUED 1036 AM EST SAT DEC 20 2014/

UPDATE...

MAIN CHANGES FOR THIS MORNING ARE WITH POPS...INCREASED POPS IN
AREAS WHERE RAIN CONTINUES AND IS EXPECTED BUT ALSO SPEEDED UP
THE EXIT ESPECIALLY FROM METRO ATLANTA AND OTHER NORTHERN ZONES
BASED ON TRENDS. TEMPERATURES LOOK OKAY UNDER WIDESPREAD CLOUD
COVER BUT WILL CONTINUE TO MONITOR IN CASE ANY BREAKS BEGIN TO
DEVELOP. OTHERWISE GRIDS LOOK GOOD...PRODUCTS WILL BE REFRESHED
SHORTLY.

TDP

PREV DISCUSSION... /ISSUED 627 AM EST SAT DEC 20 2014/

PREV DISCUSSION... /ISSUED 310 AM EST SAT DEC 20 2014/

SHORT TERM /TODAY THROUGH SUNDAY/...
CURRENT RADAR LOOP SHOWS SHOWERS SPREADING EAST ACROSS
THE STATE THIS MORNING. INSTABILITIES ARE VERY LOW THIS MORNING SO
NO THUNDERSTORMS ARE OCCURRING WITH THESE SHOWERS. AFTER THE
SHORTWAVE MOVING ACROSS THE AREA PUSHES EAST OF THE STATE THIS
AFTERNOON...NEARLY ZONAL FLOW DEVELOPS ALOFT. THE SURFACE HIGH NOW
OVER THE GREAT LAKES STATES SHIFTS EAST INTO EASTERN CANADA AND
BEGINS WEDGING DOWN THE EASTERN SEABOARD THIS AFTERNOON THROUGH
TONIGHT. THIS WILL KEEP CLOUD COVER OVER GA THROUGH SUNDAY NIGHT AS
NEXT RAIN MAKER MOVES IN. NEXT SHORTWAVE IS BEGINNING TO DEVELOP
ALONG THE EASTERN MEXICAN COAST AND WILL MOVE NE TONIGHT AND SUNDAY.
RAIN WILL MOVE BACK INTO THE STATE FROM THE SOUTH BEGINNING SUN
MORNING INCREASING NORTHWARD THROUGH SUNDAY NIGHT. WITH THE WEDGE IN
PLACE ACROSS THE AREA AHEAD OF THIS SECOND SYSTEM INSTABILITIES WILL
CONTINUE TO BE WEAK...SO NOT EXPECTING ANY THUNDERSTORMS WITH THIS
SYSTEM EITHER.

01

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
AN ACTIVE WEATHER PATTERN LOOKS TO CONTINUE DURING THE LONG TERM.

A DAMMED AIR MASS WILL BE IN PLACE SUNDAY NIGHT AND MONDAY WITH A
STATIONARY FRONT TO THE SOUTH OF THE AREA. A SURGE OF DEEPER MOISTURE
MOVES ACROSS THE AREA ALLOWING FOR LIKELY TO OCCASIONAL LIGHT RAIN
AND OCCASIONAL DRIZZLE WITH POPS DECREASING SOME FOR MONDAY.
FORECAST LOW TEMPERATURES SUNDAY NIGHT ARE RUNNING 5-10 DEGREES
ABOVE NORMAL. FORECAST HIGH TEMPERATURES ON MONDAY ARE RUNNING NEAR
TO 5 DEGREES BELOW NORMAL.

THE MAIN CONCERN THEN BECOMES THE POTENTIAL FOR SEVERE WEATHER LATE
TUESDAY AND TUESDAY NIGHT. LATEST RUNS OF THE GFS AND EUROPEAN ARE
GENERALLY SIMILAR WITH THE GFS JUST SLIGHTLY FASTER BUT WITH BOTH
MODELS SEEMING A LITTLE SLOWER THAN THE PREVIOUS RUNS. A STRONG COLD
FRONT MOVES INTO AND POSSIBLY ACROSS THE AREA TUESDAY NIGHT. A 40-50
KNOT 850MB JET WITH A STRONG UPPER JET. CAPES LOOK TO BE THE 200-800
RANGE WITH LOW LEVEL SHEAR OF 30-40 KNOTS. THE CAPES DOES NOT A LINE
ALL THAT WELL WITH THE BEST DYNAMICS BUT THE DYNAMICS ARE STRONG AS
A WARM FRONT MOVES NORTH OVER THE AREA AHEAD OF THE COLD FRONT. THIS
WILL LEAD TO STRONG TO POSSIBLY SEVERE THUNDERSTORMS WITH STRONG
WINDS AND ISOLATED TORNADOES THE MAIN THREATS.

DEPENDING ON TIMING SOME THREAT COULD LINGER ON THE EAST SIDE OF THE
FORECAST AREA TO START WEDNESDAY...BUT FOR NOW...WILL LEAVE
THUNDERSTORMS OUT ON WEDNESDAY. SOME CHANCE FOR SHOWERS WILL
CONTINUE EARLY WEDNESDAY AS THE UPPER TROUGH APPROACHES...AND THE
CHANCE FOR SHOWERS WILL CONTINUE OVER MAINLY N GA IN THE AFTERNOON.

THE UPPER TROUGH WILL BE PASSING WEDNESDAY NIGHT WITH A MUCH COLDER
AIRMASS MOVING OVER THE AREA. A CHANCE OF SHOWERS EARLY OVER N GA
WILL BECOME A CHANCE OF FLURRIES LATE NIGHT. IT LOOKS THAT THE
DEEPER MOISTURE WILL BE EXITING QUICKLY WEDNESDAY NIGHT SO NO MORE
THAN FLURRIES ARE EXPECTED AT THIS TIME.

THE FORECAST FOR CHRISTMAS IS EXPECTED TO BE DRY WITH TEMPERATURES
CLOSE TO NORMAL.

THE EUROPEAN AND GFS ARE SIGNIFICANT DIFFERENT FRIDAY INTO SATURDAY
WITH THE EUROPEAN MUCH WETTER...ESPECIALLY FRIDAY NIGHT AND SATURDAY.

BDL

&&

.AVIATION...
18Z UPDATE...
WIDESPREAD MVFR THIS AFTERNOON WITH PATCHES OF IFR CIGS. WILL
CONTINUE TREND WITH ONLY MINIMAL IMPROVEMENT THROUGH THE
AFTERNOON...SHOULD SEE MVFR EVERYWHERE. CIGS DROP AGAIN OVERNIGHT
WITH HINTS AT LIFR CONDITIONS AS WELL AS IFR FOG. SOME HINTS AT
LIFR FOG. ONLY SLOW IMPROVEMENT LATE SUNDAY MORNING WITH LOW MVFR
EXPECTED THROUGH THE END OF THE PERIOD. WINDS FAVORING THE E SIDE
THROUGH THE PERIOD BUT CANNOT RULE OUT BRIEF NNW WINDS THIS
AFTERNOON...BUT GENERALLY ALL 5KT OR LESS.

//ATL CONFIDENCE...18Z UPDATE...
MEDIUM-HIGH ON WIND DIRECTION THIS AFTERNOON.
MEDIUM ON TIMING OF CIGS BUT HIGH ON GENERAL TRENDS.
MEDIUM ON VSBY REMAINING 2SM OR GREATER.

TDP

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          51  38  51  40 / 100   5  30  60
ATLANTA         53  42  52  43 / 100   5  30  50
BLAIRSVILLE     49  36  50  39 /  30  10  20  50
CARTERSVILLE    53  37  52  40 /  50  10  20  30
COLUMBUS        55  45  55  46 / 100  20  40  50
GAINESVILLE     50  38  50  41 /  70   5  30  50
MACON           55  43  54  46 / 100  20  50  60
ROME            52  35  54  40 /  10   5  20  30
PEACHTREE CITY  54  37  52  42 / 100   5  30  50
VIDALIA         56  45  56  49 / 100  20  60  80

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$


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